Direct 3D Printing of High-Mass-Loaded Metal–Organic Framework Filaments with Excellent Adsorption Ability

Abstract

Conferring adsorptive properties to 3D printed materials by functionalizing thermoplastic polymers with metal–organic framework (MOF) materials paves the way for fused deposition modeling (FDM) 3D printing. However, to maintain the flexibility of the filament for printing, a low MOF loading mass (<10 wt %) must be maintained, which undesirably reduces the adsorption capability of the printed materials. In this study, 50 wt % HKUST-1 MOF is loaded into polyethylene glycol dimethyl ether (PEGDME) plasticized polylactic acid (PLA) to form a composite (HK@PLA–PEG-50). The high mass loading is achieved by the introduction of PEGDME as a plasticizer and the preparation of a homogeneous composite slurry. Without the post-printing process, the printed sorbent material with a high surface area of 547 m² g^–1 (49% relative to that of the originally prepared HKUST-1) has a CO₂ adsorption capacity of 37.7 cm³ g^–1 at 1 atm and 298 K, with a removal efficiency of 93.4% for 18 mg L^–1 methylene blue (MB) solution. These results prove that HKUST-1 in the filament exhibits adsorption ability without hindrance from the polymer portion, which resulted from the high mass loading of HKUST-1 and led to the interconnection between the particles, thereby avoiding the blocking effect of the PLA polymer. This study demonstrates a promising method for preparing high-mass-loading HKUST-1 composite materials for FDM 3D printing and opens up the possibility of loading other MOF materials with unique properties into polymers for diverse applications.